Thumbnailer fails with requested `width=0` or `height=0`

[matrixbot]

This issue has been migrated from #14579.

---

Description

If you request a thumbnail with width=0&height=0 (for both scale and crop)

• container image returns HTTP 500
• Ubuntu package returns the image

I cannot explain why the platforms behave differently.
In any case, validation of the rest API is missing (#13147).

Steps to reproduce

Ubuntu package deployment

• request an thumbnail image (eg. profile image)
  • HTTP GET https://example.com/_matrix/media/r0/thumbnail/example.com/<media_id>?width=0&height=0&method=scale
  • you get the image

container deployment

• request an thumbnail image (eg. profile image)
  • HTTP GET https://example.com/_matrix/media/r0/thumbnail/example.com/<media_id>?width=0&height=0&method=scale
  • you get an error HTTP 500: {"errcode":"M_UNKNOWN","error":"Internal server error"}

2022-11-29 09:40:59,762 - synapse.http.server - 124 - ERROR - GET-13- Failed handle request via 'ThumbnailResource': <XForwardedForRequest at 0x7f46681b7220 method='GET' uri='/_matrix/media/r0/thumbnail/k8s.azure.kird.net/qQlsITBVkgBeIrbvLpbByOOy?width=0&height=0&method=scale' clientproto='HTTP/1.1' site='8083'>
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/synapse/http/server.py", line 307, in _async_render_wrapper
    callback_return = await self._async_render(request)
  File "/usr/local/lib/python3.9/site-packages/synapse/http/server.py", line 337, in _async_render
    callback_return = await raw_callback_return
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnail_resource.py", line 76, in _async_render_GET
    await self._select_or_generate_local_thumbnail(
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnail_resource.py", line 178, in _select_or_generate_local_thumbnail
    file_path = await self.media_repo.generate_local_exact_thumbnail(
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/media_repository.py", line 592, in generate_local_exact_thumbnail
    t_byte_source = await defer_to_thread(-packages/synapse/rest/media/v1/thumbnail_resource.py", line 178, in _select_or_generate_local_thumbnail
    file_path = await self.media_repo.generate_local_exact_thumbnail(
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/media_repository.py", line 592, in generate_local_exact_thumbnail
    t_byte_source = await defer_to_thread(
  File "/usr/local/lib/python3.9/site-packages/twisted/python/threadpool.py", line 244, in inContext
    result = inContext.theWork()  # type: ignore[attr-de
  File "/usr/local/lib/python3.9/site-packages/twisted/python/threadpool.py", line 244, in inContext
    result = inContext.theWork()  # type: ignore[attr-defined]
  File "/usr/local/lib/python3.9/site-packages/twisted/python/threadpool.py", line 260, in <lambda>
    inContext.theWork = lambda: context.call(  # type: ignore[attr-defined]
  File "/usr/local/lib/python3.9/site-packages/twisted/python/context.py", line 117, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/local/lib/python3.9/site-packages/twisted/python/context.py", line 82, in callWithContext
    return func(*args, **kw)
  File "/usr/local/lib/python3.9/site-packages/synapse/logging/context.py", line 970, in g
    return f(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/media_repository.py", line 562, in _generate_thumbnail
    return thumbnailer.scale(t_width, t_height, t_type)
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnailer.py", line 143, in scale
    with self._resize(width, height) as scaled:
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnailer.py", line 135, in _resize
    return self.image.resize((width, height), Image.ANTIALIAS)
  File "/usr/local/lib/python3.9/site-packages/PIL/Image.py", line 2115, in resize
    return self._new(self.im.resize(size, resample, box))
ValueError: height and width must be > 0

I am did the same image for both plattforms / servers.

Homeserver

another homeserver

Synapse Version

various

Installation Method

Other (please mention below)

Database

single PostgreSQL server

Workers

Multiple workers

Platform

• Container / K8s platform:
  • Synapse v1.64.0 and 1.72.0 (matrixdotorg/synapse:latest)
• Debian/Ubuntu platform
  • Synapse v1.71.0 (matrix.org package)

Configuration

No response

Relevant log output

see above

Anything else that would be useful to know?

container version:

cat /usr/local/lib/python3.9/site-packages/PIL/_version.py 
# Master version for Pillow
__version__ = "9.3.0

package version:

cat /opt/venvs/matrix-synapse/lib/python3.8/site-packages/PIL/_version.py 
# Master version for Pillow
__version__ = "9.2.0"